HVAC Control in the New Millennium.pdf - HVAC.Amickracing

HVAC Control in the New Millenniumranging from devices to plantwide data servers. Windows 2000 is designedto replace NT as a crashproof networking system. The WindowsMillennium Edition (ME) should be the new personal operating system.It should have many features that were promised but lacking in Windows98. Microsoft also has its Windows Distributed InterNet Applicationsarchitecture, which integrates Web and client/server computing.Windows CE is evolving as the platform of choice for embeddedHMIs and controllers. Microsoft’s component object model (COM) anddistributed component object model (DCOM) are the glue that holdssystems together.Sun Microsystems is also making an impact in the automation areawith Java and the potential of software that can be written once and runanywhere. Sun supports control systems with its Java Control and AutomationFramework initiative. Java-based browsers and componentsare also available for automation. In the embedded controller area thereis EmbeddedJava and PersonalJava. There is a range of standard productswith real-time extensions to Windows NT and CE, Java, and OLEfor process control (OPC).The Object Management Group (OMG) has a standard for distributedobject computing called CORBA (Common Object Request BrokerArchitecture). CORBA competes with Microsoft’s DCOM. The CORBAmodel was used by Foxboro to develop the Foxboro I/A Object Manager.Another trend involves Enterprise Java Beans (EJB). Distributedapplicationsprogramming is becoming an enabler of Internet technology.All of this advances Object-oriented Remote Procedure Call (ORPC)programming which is a programming model that allows developers toeasily create distributed applications.The increased interest in distributed-application programming coincideswith the growth of the Internet. Technologies such as DCOM,CORBA and EJB use the notion of location transparency.This is an abstraction that allows a programmer to call on an objectwithout knowing where that object actually resides. Programmers areallowed to program in the context of a familiar model. DCOM defineswhat an object is at a binary level.Object-oriented programming is superior over earlier developmentmethods since it simplifies the development of complex applications.Object-oriented programs communicate by sending messages betweendifferent objects. It takes at least one physical network round-trip to©2001 by The Fairmont Press, Inc. All rights reserved.